Air conduction system for a vehicle

ABSTRACT

An air duct system of an internal combustion engine comprising various components disposed at various points in the engine compartment of the motor vehicle. The air duct system includes a gas guide chamber that leads through the air duct system via a course such that only a small total installation space is needed. Part of the air duct system is curved, and the curved region has another part of the gas guide chamber that passes through it. The air duct system is intended in particular for an internal combustion engine of a motor vehicle.

The air duct system is intended in particular for a motor vehicle. Inpreviously known air duct systems, the various components of the airduct system are secured at various points of the body of the motorvehicle. In one known air duct system, for instance, a gas guide chamberleads from an air inlet opening of the air duct system to an air filtersecured for instance to the wheelwell of the motor vehicle body. Fromthe air filter, the gas guide chamber then leads on, for instance to athrottle device with a throttle valve pivotably supported in it.Downstream of the throttle device, the gas guide chamber splits into aplurality of conduits leading to cylinders. The number of conduits isequivalent to the number of cylinders of the engine.

A disadvantage of the known air duct system is that it needs a largeamount of space overall in the motor vehicle engine compartment, so thatless space is then available for other motor vehicle equipment in theengine compartment. Alternatively, because only a certain amount ofinstallation space is made available to the air duct system, the airduct system or the useful internal volume of the gas guide chamber ofthe air duct system cannot be made as large as would be needed foroptimal functions of the air duct system. Hence compromises must bemade, which do not always lead to an outcome that is satisfactory inevery respective.

In addition, the known air duct system involves major effort and expensefor installation in the engine compartment of the motor vehicle.

ADVANTAGES OF THE INVENTION

The air duct system according to the invention has the advantage overthe prior art that while having a large internal useful volume, the airduct system overall requires only little installation space. In the airduct system, the available installation space is advantageously utilizedespecially well.

Mounting the air duct system on the engine, or its installation in themotor vehicle, is additionally and advantageously especially simple andrequires little mounting effort or expense.

By means of the provisions recited herein, advantageous further featuresof and improvements to the air duct system recited are possible.

If a spirally shaped curved region is located downstream of theinterpenetrating region, in terms of the direction of the air flowingthrough the air duct system, then the available installation space canadvantageously be utilized especially.

If the spirally shaped curved region is located upstream of the outletopening of the air duct system, then an especially favorable guidance ofthe air is advantageously achieved.

If the interpenetrating region is located downstream of the air inletopening by a relatively short distance, then still further improvementis obtained in the utilization of the available installation space.

In the course between the air inlet opening and the outlet opening, anair filter may be provided, and the effort and expense and requisiteinstallation space for this air filter are advantageously especiallyslight.

The region between the interpenetrating region and the spirally shapedcurved region is advantageously especially suitable for the provision ofthe air filter.

In the region between the air inlet opening and the outlet opening ofthe air duct system, a throttle device can advantageously be providedwithout major effort or expense.

If the engine has two or more cylinders, and if the gas guide chamber istherefore split into two or more conduits in the region upstream of theoutlet opening of the air duct system, for instance, and theinterpenetrating region is passed between the at least two conduits,then an especially expedient utilization of the available installationspace is advantageously obtained. Unutilized regions are largely avoidedin the available installation space for the air duct system.

If at least part of the cylinder head hood is used to form at least aportion of the gas guide chamber, then advantageously only a fewcomponents in all are needed, and the available installation space canbe utilized especially well. The mounting effort and expense when theair duct system is installed on the engine are especially low.

If the cylinder head hood is used to hold or carry the air filter, thenadvantageously a still further reduction in the requisite mountingeffort and expense is obtained, and the number of components required isadvantageously especially low.

If a design cap is provided, at least part of which forms a portion ofthe gas guide chamber, then a visually attractive appearance of the airduct system is obtained, and in addition only a few components in allare needed, and the available installation space is utilized especiallywell.

BRIEF DESCRIPTION OF THE DRAWING

Especially selected and especially advantageous exemplary embodiments ofthe invention are shown in simplified form in the drawing and describedin further detail in the ensuing description. FIGS. 1-8 show varioussections and views of air duct systems selected as examples.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The air duct system embodied according to the invention may be providedin various internal combustion engines. The engine is for instance amotor to which air or a fuel-air mixture is delivered via the air ductsystem. The air duct system can be combined structurally with variouscomponents required for operating the engine.

The engine is an aspirating engine, for instance, in which air isaspirated by suitable motion of the pistons. However, it is alsopossible to provide an additional unit that delivers the air underpressure to the engine.

The engine preferably has multiple cylinders, but it may in principle bean internal combustion engine with only a single cylinder.

Although the engine may be of various types and can be used to drivedifferent machines, for the sake of simplicity in the ensuingdescription of the exemplary embodiments it is assumed that the engineoperates by the principle of an Otto engine, is an aspirating engine, isinstalled in the engine compartment of a motor vehicle, and is used todrive the motor vehicle. It is also assumed that the engine includesfour in-line cylinders, with the line of four cylinders being installedcrosswise to the travel direction of the motor vehicle.

FIG. 1 shows a cross section through the air duct system. The sectionalplane shown extends longitudinally to the travel direction of the motorvehicle.

FIG. 2 shows a longitudinal section through the air duct system; thesectional plane of FIG. 2 extends at right angles to the sectional planeshown in FIG. 1, or in other words extends crosswise to the traveldirection.

For the sake of better comprehension, the sectional faces shown in FIGS.1 and 2 do not each extend in a single plane but instead are graduatedmultiple times, to make the essence of the invention as clear aspossible.

FIG. 3 is a view on the air duct system obliquely from the front,somewhat above the air duct system.

In all the drawing figures, elements that are the same or function thesame are provided with the same reference numerals. Unless otherwisementioned or shown in the drawing, what is said about and shown in oneof the figures applies to all the exemplary embodiments. Unlessotherwise stated in the explanations, the details of the variousexemplary embodiments can be combined with one another.

The exemplary embodiment of the air duct system 2 selected as thepreferred embodiment for the description and the drawing is composedessentially of a first air duct part 4, a second air duct part 6, a tube8, and a design hood 10. In approximate terms, the first air duct part4, second air duct part 6, tube 8 and design hood 10 are the primarycomponents of the air duct system 2.

FIG. 4 shows a portion of the air duct system 2. FIG. 4 essentiallyshows the first air duct part 4 and the tube 8. For the sake of bettercomprehension, the second air duct part 6 and the design hood 10 are notshown in FIG. 4.

FIG. 5 shows a further view from a different direction of the first airduct part 4. FIG. 6 essentially shows the second air duct part 6 in anoblique view from above.

FIG. 7 is again a view of the second air duct part 6 from a directiondifferent from FIG. 6.

In the ensuing description, the drawing figure (FIG.) that especiallyclearly shows the particular detail is repeatedly given in parentheses.

The selected internal combustion engine has four cylinders and acylinder head 12. A small portion of a section through the cylinder head12 of the engine is shown (FIG. 1). For the sake of bettercomprehension, essentially only the outlines of the section through thecylinder head 12 are shown.

The cylinder head 12 belongs to an engine having at least one cylinder.In the cylinder, there is a displaceably supported piston (not shown,for the sake of simplicity) and a combustion chamber (also not shown,for the sake of simplicity). A gas inlet opening 14 leads into theengine combustion chamber. Through the gas inlet opening 14, air or afuel-air mixture can reach the combustion chamber.

The air duct system 2 has an air inlet opening 16 (FIGS. 1, 2) and anoutlet opening 18 (FIG. 1). A gas guide tube leads through the air ductsystem 2. The gas guide tube will hereinafter be called the gas guidechamber 20. The gas guide chamber 20 begins at the air inlet opening 16and leads via the outlet opening 18 into the gas inlet opening 14 of thecylinder head 12 of the engine.

Through the gas guide chamber 20, air can flow through the air inletopening 16 and reach the engine combustion chamber. In the course of theair duct system 2, the air flowing through it can be supplied with fuelor a mixture, depending on the engine type and as needed.

To simplify the explanation of the exemplary embodiments, the gas guidechamber 20 will be thought of below as being subdivided into a pluralityof parts. In this imaginary subdivision, the gas guide chamber 20,beginning at the air inlet opening 16, has an inlet conduit 21 (firstpart 21 of the gas guide chamber 20) (FIG. 2). The inlet conduit 21 isfollowed downstream by a fresh air chamber or air chamber 22 (secondpart 22 of the gas guide chamber 20) (FIGS. 1, 2). In terms of the flowdirection, the air chamber 22 is divided into three fresh air conduits23 (third part 23 of the gas guide chamber 20) (FIG. 2). The fresh airconduits 23 are united again in a prefilter chamber 24 (fourth part 24of the gas guide chamber 20). The prefilter chamber 24 is locatedupstream of a filter installation space 25 (fifth part 25) of the gasguide chamber 20). Following is the filter installation space 25 is apostfilter chamber 26 (sixth part 26 of the gas guide chamber 20) (FIGS.1, 2). Following the postfilter chamber 26, in terms of the flowdirection, is a calming conduit 27 (seventh part 27 of the gas guidechamber 20) (FIGS. 1, 2, 6). The calming conduit 27 is followed by aconnecting conduit 28 (eighth part 28 of the gas guide chamber 20) (FIG.2). The connecting conduit 28 is located substantially inside theflexible tube 8. The connecting conduit 28 ends downstream in a throttledevice 29 (ninth part 29 of the gas guide chamber 20) (FIGS. 2, 3). Thisis followed downstream by a connecting stub 30 (tenth part 30 of the gasguide chamber 20) (FIG. 2). The connecting stub 30 discharges into a gasdistribution chamber 31 (eleventh part 31 of the gas guide chamber 20)(FIGS. 1, 2). A conduit 32 (twelfth part 32 of the gas guide chamber 20)branches off from the gas distribution chamber 31 (FIGS. 1, 2, 3).

The conduit 32 carries the medium, or some of it, flowing through theair duct system 2 from the gas distribution chamber 31 through theoutlet opening 18 and the gas inlet opening 14 to the combustion chamberof the engine.

Since the air duct system 2 selected as the preferred embodiment isintended for instance for an internal combustion engine with fourcombustion chambers, three further conduits 32a, 32b, 32c (FIGS. 2, 5)branch off, parallel to the conduit 32, from the gas distributionchamber 31; each of these conduits 32, 32a, 32b, 32c leads to arespective combustion chamber of the four-cylinder engine.

The inlet conduit 21, the air chamber 22, the fresh air conduit 23, andpart of the prefilter chamber 24 belong to a tubular region of the airduct system 2 that will hereinafter be called the interpenetratingregion 38. The air duct system 2 can also be embodied in such a way thatsome of these components are located outside the interpenetrating region38.

In terms of the longitudinal direction of the gas distribution chamber31, the conduits 32, 32a, 32b, 32c branch off virtually at a right anglefrom the gas distribution chamber 31. The conduits 32, 32a, 32b, 32cform a spirally shaped curved region 40 (FIG. 1) of the air duct system2. In approximate terms, the curved region 40 can be imagined ascomprising a first portion 41, a second portion 42 and a third portion43.

The first portion 41 begins, in terms of the flow direction, at thepoint where the conduits 32, 32a, 32b, 32c branch off from the gasdistribution chamber 31. In the first portion 41, the conduits 32, 32a,32b, 32c communicate with one another via a wall 46 (FIG. 2). The firstportion 41 of the conduits 32, 32a, 32b, 32c (FIG. 2) is located on theoutward-facing side of the wall 46, and the air chamber 22 is located onthe inward-facing side of the wall 46. The wall 46 partitions the airchamber 22 off from the environment, and the wall 46 also serves topartition off the conduits 32, 32a, 32b, 32c from the air chamber 22. Inthe first portion 41, the conduits 32, 32a, 32b, 32c extend in a curve(a clockwise curve of approximately 90° in terms of the viewingdirection of FIG. 1). The curve is followed by a short straight piece.The end of the first portion 41 can be imagined as placed at the end ofthe straight piece.

The second portion 42 of the curved region 40 adjoins the first portion41. The conduits 32, 32a, 32b, 32c are extended in a further curve(clockwise curve of approximately 120°, for instance, in terms of theview of FIG. 1) in the second portion 42. In the second portion 42, theconduits 32, 32a, 32b, 32c are spaced apart from one another, so thatthere are gaps between the conduits 32, 32a, 32b, 32c that serve toconnect the air chamber 22 of the fresh-air conduit 23 with theprefilter chamber 24 (FIGS. 2, 5). The air can flow out of the airchamber 22 through the conduits 32, 32a, 32b, 32c in the direction ofthe prefilter chamber 24.

In the exemplary embodiment shown in the drawing, there are three gapsin the conduits 32, 32a, 32b, 32c. Through these three gaps, thefresh-air conduit 23 (FIG. 3) leads out of the air chamber 22 into theprefilter chamber 24. Since the engine selected as an example has fourcylinders, the three gaps result between the conduits 32, 32a, 32b, 32c,and therefore the freshair conduit 23 is divided up into three regionsthat carry the air parallel. The fresh-air conduit 23 makes optimal useof the gaps between the conduits 32, 32a, 32b, 32c, so that no unusableroom is wasted between the conduits 32, 32a, 32b, 32c.

The third portion 43 (FIG. 1) then comes, adjoining the second portion42. In the third portion 43, the conduits 32, 32a, 32b, 32c are thensubstantially straight until each of the conduits 32, 32a, 32b, 32c endat a respective outlet opening 18. A wall 47 (FIG. 5) inserted betweenthe conduits 32, 32a, 32b, 32c and the third portion 43 partitions offthe air chamber 22 from the environment.

The conduits 32, 32a, 32b, 32c are curved spirally. By way of example,the conduits 32, 32a, 32b, 32c are curved by a total of 180° in thethree portions 41, 42, 43. As FIG. 1 shows, the conduits 32, 32a, 32b,32c can in particular also be curved by more than 180°. The so-calledspirally shaped curved region 40 at least partially encompasses theinterpenetrating region 38.

The conduits 32, 32a, 32b, 32c have a cross section that in its form isapproximately equivalent to the cross section, greatly reduced, of ahighway tunnel (FIG. 2).

On the cylinder head 12 of the engine, there is a chamber 48 (FIG. 1).Located in the chamber 48 are for instance the typical injection valvesand outlet valves for an internal combustion engine and the controlshaft for controlling the inlet and outlet valves. The control shaft,inlet and outlet valves are not shown, for the sake of greatersimplicity. The chamber 48 (FIG. 1) is covered with the aid of acylinder head hood 50 (FIGS. 1, 6). An oil fill stub 52 and a connection54 are formed onto the cylinder head hood 50. Lines leading into thechamber 48 and out of the chamber 48 can be connected to the connection54.

The cylinder head hood 50 is shaped such that it can be used both tocover the chamber 48 of the cylinder head 12 and for forming the secondair duct part 6 of the air duct system 2 (FIG. 6). In other words, thesecond air duct part 6 is shaped such that it is both a component of theair duct system 2 and can serve to cover the chamber 48 of the engine.The second air duct part 6 shown in FIG. 6, with the cylinder head hood50 formed onto it, can be made in one piece, cohesively, using aninjection mold. The material comprising the second air duct part 6 ispreferably plastic.

The second air duct part 6 is shaped such that the filter installationspace 25 (FIG. 6) is formed in it. Next to it, the second air duct part6 also forms the calming conduit 27 (seventh portion of the gas guidechamber 20) (FIGS. 1, 2, 6). An air filter 56 (FIGS. 1, 2, 7) is locatedin the filter installation space 25. The air filter 56 substantiallycomprises a filter cartridge that is placed in the filter installationspace 25. An encompassing seal 58 (FIGS. 1, 2) is provided on the filtercartridge of the air filter 56. The seal 58 seals off the air filter 56from the air duct part 6 or the design hood 10 (FIGS. 1, 2), so that noair can escape from the prefilter chamber 24 into the postfilter chamber26 while bypassing the air filter 56.

Because of the air filter 56, the regions upstream of the air filter 56,which include the inlet conduit 21, the air chamber 22, the fresh-airconduit 23 and the prefilter chamber 24, can be called the fresh-airchamber 60 (FIG. 2). Correspondingly, the regions of the air duct system2 that are located downstream of the air filter 56 can be called theclean-air chamber 62. The clean-air chamber 62 includes the postfilterchamber 26, the calming conduit 27, the connecting conduit 28, theinternal region of the throttle device 29, the connecting stub 30, thegas distribution chamber 31, and the conduits 32, 32a, 32b, 32c.

A connection opening 64 (FIGS. 2, 7) is formed onto the second air ductpart 6. The connection opening 64 discharges into the calming conduit27. A flow rate meter 66 (FIG. 7) is provided in the connection opening64. The flow rate meter 66 can sense the volume or mass of air flowingthrough the gas guide chamber 20 per unit of time and furnish anelectrical signal accordingly to an electronic system, not shown. Inaddition to or instead of the flow rate meter 66, a temperature meterthat measures the temperature of the air flowing through can be builtinto the connection opening 64.

Upstream of the flow rate meter 66 in the calming conduit 27, a metalscreen 68 (FIG. 2) and/or a flow lattice 68a molded from plastic areprovided. The screen 68 and the flow lattice 68a promote the calming ofthe air approaching the flow rate meter 66.

The second air duct part 6 of the air duct system 2, which also takes onthe function of the cylinder head hood 50, is connected to the cylinderhead 12 of the engine via one fastening means 70 (FIG. 1) or more thanone fastening means 70. The fastening means 70 is in the form of one ormore screws, for instance, with which the air duct part 6 is firmlyconnected to the engine. Between the cylinder head 12 and the air ductpart 6, an encompassing cylinder head seal 72 (FIG. 1) is provided,which seals off the chamber 48 from the environment.

The second air duct part 6 is firmly, but releasably as needed,connected to the first air duct part 4 via a fastening means 74 (FIG.1). The fastening means 74 by way of example includes one or more clampsdistributed over the circumference. By way of example, the clamps of thefastening means 74 are pivotably supported on the second air duct part 6and, after the second air duct part 6 is mounted on the first air ductpart 4, can snap into place on corresponding cams provided on the firstair duct part 4.

The shapes of the first air duct part 4 and second air duct part 6 areadapted to one another in such a way that a cavity, which is a componentof the gas guide chamber 20, is formed between the first air duct part 4and the second air duct part 6. Located in the cavity by way of exampleare in particular the prefilter chamber 24 and the filter installationspace 25. A housing seal 76 (FIGS. 1, 2) is provided between the firstair duct part 4 and the second air duct part 6. The housing seal 76seals off the gas guide chamber 20 from the environment.

The design hood 10 is mounted on the second air duct part 6. The shapesof the design hood 10 and of the second air duct part 6 are adapted toone another in such a way that a cavity, which is a component of thepostfilter chamber 26, is formed between the design hood 10 and thesecond air duct part 6. This cavity essentially belongs to the clean-airchamber 62. The cavity between the design hood 10 and the second airduct part 6 extends not only in the region directly downstream of thefilter 56 but also far into the region located above the cylinder hood50 that covers the chamber 48. As a result, an additional chamber 78(FIGS. 1, 7) is created between the design hood 10 and the second airduct part 6. The chamber 78 is located not directly in the flow of airbut rather somewhat to the side of it. For the sake of reinforcement andsecure holding of the air filter 56, intermediate ribs are providedbetween the design hood 10 and the air duct part 6. Openings are locatedin the intermediate ribs, so that the additional chamber 78 communicatesdirectly with the gas guide chamber 20. The additional chamber 78volumetrically increases the usable volume redundant! of the gas guidechamber 20. This has major influence on the noise produced by theengine. Because the gas guide chamber 20 can be made rather large, evenif external space is restricted, the noise production of the air ductsystem 2 or engine can be reduced substantially.

The design hood 10 is connected firmly, but releasably as needed (FIG.1), with the second air duct part 6 via a fastening means 80. Thefastening means 80 for instance includes one hinge 80a or a plurality ofhinges 80a, one screw 80b or a plurality of screws 80b, and one clamp80c or a plurality of clamps 80c. Depending on the number of screws 80b,the fastening means 80 also includes one nut thread 80d (FIGS. 1, 6), ora plurality of nut threads 80d, formed or cut onto the air duct part 6,for screwing in the screw 80b or screws 80b for securing the design hood10 to the air duct part 6. After the clamp 80c and screw 80b have beenloosened, the design hood 10 can be swiveled relative to the air ductpart 6, and the air filter 56 can for instance be checked or replaced.

At points of contact between the design hood 10 and the second air ductpart 6, an encompassing seal 82 is provided. The seal 82 is also mountedon the intermediate ribs between the air duct part 6 and the design hood10.

The cylinder head seal 72, the housing seal 76 between the two air ductparts 4 and 6, and the seal 82 serves the purpose of sealing off andacoustically uncoupling the various components and thus have anoise-abating effect.

In the air duct system 2, a fuel delivery opening 84 (FIGS. 1, 5) isprovided. As the preferred selected exemplary embodiment shows, the fueldelivery opening 84 extends in the region of the outlet opening 18 intothe gas guide chamber 20. Depending on the number of conduits 32, 32a,32b, 32c, a corresponding number of fuel delivery openings 84, 84a, 84b,84c (FIG. 5) is provided.

A fuel distributor strip 86 (FIG. 1) is mounted onto the air duct system2. The fuel distributor strip 86 includes a fuel tube 88, anelectrically actuatable injection valve 90 (FIG. 1), and a fuelconnection stub 92. One injection valve 90 (FIG. 1) is inserted intoeach of the fuel delivery openings 84, 84a, 84b, 84c (FIG. 5).

Each of these four injection valves 90 branches off from the fuel tube88. For the sake of simplicity, only one of the injection valves 90 isshown in FIG. 1. Via a fuel pump, not shown, the fuel passes via thefuel connection stub 92 to reach the fuel tube 88. Via the fuel tube 88,the injection valves 90, for instance the four such injection valves,are supplied with fuel and the injection valves 90 inject the fuel,controlled by a control unit, in metered fashion via the gas inletopening 14 into the engine combustion chamber. In the region of the gasinlet opening 14, intensive mixing of the fuel with the aid delivered tothe engine via the air duct system 2 takes place.

Between the first air duct part 4 and the second air duct part 6, acavity 94 extending along the four cylinders, for instance, of theengine is formed. The fuel distributor strip 86 having the injectionvalves 90 can be disposed in this cavity 94. The fuel distributor strip86 is thus protected against damage and, since it is not visible fromabove, a largely smooth-surfaced and therefore visually attractiveappearance of the air duct system 2 is achieved. Since the fasteningmeans 70 and 74 are designed such that the air duct part 6 with thedesign hood 10 can easily be removed, the fuel distributor strip 86 iseasily accessible as needed.

There are two fastening threads 96 and 96c (FIG. 5) on the first airduct part 4. The fastening threads 96, 96c are provided so that the fueldistributor strip 86 with the injection valves 90 can be connectedfirmly but releasably to the air duct part 4 via fastening screws. Thefastening screws are not shown, for the sake of simplicity.

In FIG. 1, a dot-dashed line 98 that gas multiple angle bends is shown.The dot-dashed line 98 on the one hand and the cylinder head 12 of theengine on the other define an installation space 100. The air ductsystem 2 is located inside the installation space 100. In many motorvehicles, the space that can be made available or is furnished for theair duct system 2 is relatively narrowly bounded. As the drawing shows,the air duct system 2 embodied according to the invention makes verygood use of the available installation space 100. The air duct system 2is designed such that despite the relatively small installation space100, the internal usable volume of the gas guide chamber 20 of the airduct system 2 is relatively large. Because of the large volume of thegas guide chamber 20, there are favorable effects in terms of noiseabatement and in terms of the degree to which the engine combustioncompartments are filled. Because the usable volume of the gas guidechamber 20 can be made relatively large, there is also a relativelylarge amount of space available for the air filter 56, so that arelatively large air filter cartridge can be built into the air ductsystem 2, which has the advantage that the length of the time that theair filter 56 can be used before the filter cartridge of the air filter56 can to be replaced is long. The particularly good utilization of theavailable installation space 100 is also due to the fact that the airduct system 2 has the spirally shaped curved region 40 and theinterpenetrating region 38 that at least partly penetrates the spirallyshaped curved region 40 and essentially includes the air chamber 22 andthe fresh-air conduit 23.

The tube 8 is connected by its upstream end to the calming conduit 27(FIG. 2) formed onto the air duct part 6, and downstream the tube 8 isconnected to the throttle device 29. The throttle device 29 ismechanically coupled to the first air duct part 4. Via the elastichousing seal 76, the two air duct parts 4 and 6 are largely decoupledfrom one another vibrationally and acoustically. The tube 8 is elasticand therefore does not, or not substantially, hinder the vibrationaldecoupling between the two air duct parts 4 and 6. By way of example,the throttle device 29 includes a throttle valve 29b (FIG. 2) pivotablysupported in a throttle valve stub 29a. The position of the throttlevalve 29b is variable, for instance with the aid of an electricallycontrollable positioner 29c (FIG. 3). The throttle device 29 thatincludes the throttle valve stub 29a, throttle valve 29b and positioner29c can be flanged as a complete unit to the first air duct part 4 ofthe air duct system 2. The positioner 29c of the throttle device 29 forinstance includes an electrically triggerable electric motor and/or anactuating lever that can be mechanically adjusted from a gas pedal, forinstance via a Bowden cable.

A retaining device 102 (FIGS. 3, 5) is provided on the preferredexemplary air duct system 2 shown. Via the retaining device 102, a tankventing valve can for instance be secured to the air duct system 2. Theretaining device 102 is for instance formed onto the connecting stub 30of the first air duct part 4.

Taken together, the air duct system 2 forms a functional unit for aninternal combustion engine and can therefore also be called an air guidemodule. The engine is often an engine that aspirates air at negativepressure. The air duct system 2 can therefore also be called an airguide module or aspiration system or aspiration module.

The air duct system 2 or air guide module or aspiration system oraspiration module can for instance be assembled, complete, at a firstproduction facility and then installed in the engine at a secondproduction facility. However, it is also possible to furnish the airduct system 2 in two separate, individual modules to the secondproduction facility and not to put them together until when they aremounted onto the engine. The first individual module (FIG. 4) forinstance substantially includes the first air duct part 4, the tube 8,the throttle device 29, and the fuel distributor strip 86 that has theinjection valves 90 and is mounted on the first air duct part 4. FIG. 4shows the components of the first individual module. A flange face 104(FIGS. 1, 5) is provided on the first air duct part 4. A counterpartflange face is located on the engine. The first air duct part 4 can besecured with its flange face 104 to the counterpart flange face of theengine. Fastening means, especially screws, not shown in the drawing areused for this fastening. The second individual module for instancesubstantially includes the second air duct part 6 with the cylinder headhood 50 formed onto it, the air filter 56 inserted into the air ductpart, the flow rate meter 66, the oil fill stub 52, and the design hood10. However, the design good 10 can also be mounted onto the enginelater, independently of the second individual module.

In the exemplary embodiment shown, the four injection valves 90 areprovided so as to meter fuel separately to each cylinder of the engine.It will be noted, however, that the air duct system 2 may also beembodied such that fuel is delivered to some other point of the air ductsystem 2. For instance, it is possible for fuel to be injected into thegas guide chamber 20 in the region of the throttle device 29, in whichcase the fuel mixes intensively with the air in the region of thethrottle device 29 and is delivered together with the air to the enginecombustion chambers. In addition it is also possible for the fuel to beinjected, via injection valves not shown, not into the air duct system 2but rather directly into the engine combustion chambers.

In the first air duct part 4, there is a first parting plane 106 and asecond parting plane 108 (FIG. 1), both curving back and forth. For easyproduction of the air duct part 4 by casting, the air duct part 4 ismade of three cast or injection-molded individual parts, which arewelded or glued together after the casting or injection molding. Sincethe first air duct part 4, like the second air duct part 6, ispreferably of plastic, it is easily possible to weld or glue the threeindividual parts together.

FIG. 8 shows a modified, preferably selected exemplary embodiment.

As in FIG. 6, FIG. 8 shows a view of the second air duct part 6, butfrom a different direction. In addition, in the exemplary embodimentshown in FIG. 8, an ignition device 110 is mounted firmly on the airduct part 6. By way of example, the ignition device 110 includes fourignition coils, and one spark plug, not shown, can be connected to eachof the four ignition coils. The ignition device 110 is preferably of adesign in which an ignition distributor can be dispensed with. Theignition device 110 serves to ignite the fuel-air mixture in thecombustion chambers of the engine.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

I claim:
 1. An air duct system, for an internal combustion enginecomprising at least two combustion chambers with at least one gas inletopening leading into the combustion chamber, an air inlet opening (16),having an outlet opening (18) connected to the gas inlet opening of thecombustion chamber, a gas guide chamber (20) which carries air from theair inlet opening (16) to the outlet opening (18), the gas guide chamber(20) has at least one spirally shaped curved region (40) which isdivided into at least two conduits (32, 32a, 32b, 32c) and oneinterpenetrating region (38) that is made to at least partly penetratethe spirally shaped curved region (40) and to pass at least partlybetween the at least two conduits.
 2. An air duct system in accordancewith claim 1, in which the spirally shaped curved region (40) is locateddownstream of the interpenetrating region (38).
 3. An air duct system inaccordance with claim 1, in which the spirally shaped curved region (40)adjoins the outlet opening (18) upstream thereof.
 4. An air duct systemin accordance with claim 2, in which the spirally shaped curved region(40) adjoins the outlet opening (18) upstream thereof.
 5. An air ductsystem in accordance with claim 1, in which the interpenetrating region(38) adjoins the air inlet opening (16) downstream thereof.
 6. An airduct system in accordance with claim 1, in which an air filter (56) isprovided between the air inlet opening (16) and the outlet opening (18).7. An air duct system in accordance with claim 6, in which the airfilter (56) is provided between the interpenetrating region (38) and thespirally shaped curved region (40).
 8. An air duct system in accordancewith claim 1, in which a throttle device (29) is provided between theair inlet opening (16) and outlet opening (18).
 9. An air duct system inaccordance with claim 8, in which the throttle device (29) is providedbetween the interpenetrating region (38) and the spirally shaped curvedregion (40).
 10. An air duct system in accordance with claim 8, in whichthe throttle device (29) is provided downstream of the air filter (56).11. An air duct system in accordance with claim 9, in which the throttledevice (29) is provided downstream of the air filter (56).
 12. An airduct system in accordance with claim 1, in which an intermediate tube(8) connects the interpenetrating region (38) with the spirally shapedcurved region (40).
 13. An air duct system in accordance with claim 1,in which the engine has a chamber (48) closed off with the aid of acylinder head hood (50), and at least part of the cylinder head hood(50) forms at least one portion of the gas guide chamber (20).
 14. Anair duct system in accordance with claim 6, in which the air filter (56)is carried by the cylinder head hood (50).
 15. An air duct system inaccordance with claim 7, in which the air filter (56) is carried by thecylinder head hood (50).
 16. An air duct system in accordance with claim6, in which the cylinder head hood (50) is intended to carry an ignitiondevice (11).
 17. An air duct system in accordance with claim 7, in whichthe cylinder head hood (50) is intended to carry an ignition device(11).
 18. An air duct system in accordance with claim 1, in which adesign hood (10) at least partially covering the engine is provided, andat least part of the design hood (10) surrounds at least a portion ofthe gas guide chamber (20).
 19. An air duct system in accordance withclaim 2, in which a design hood (10) at least partially covering theengine is provided, and at least part of the design hood (10) surroundsat least a portion of the gas guide chamber (20).
 20. An air duct systemin accordance with claim 3, in which a design hood (10) at leastpartially covering the engine is provided, and at least part of thedesign hood (10) surrounds at least a portion of the gas guide chamber(20).